On Valentine's Day in 2005 a young woman goes missing. Her name is Joanne Nelson. Her fiancé makes a desperate call to police, who initially are puzzled. Her car is at home but unlocked. But her work clothes and purse are missing. They scour the city, looking for clues to where she might be. Several days later, when her fiancé Paul Dyson appears on the news appealing for information, cops notice scratches on his hands. They look at Dyson's behaviour and find CCTV of him buying cleaning products on the day she disappeared. Within a few days he's arrested and charged. But he claims he can't remember where the body is. Detectives turn to a pollen expert who pieces together fragments of evidence to take cops to the scene where Joanne has been dumped. Cops then begin to explore whether the same science can resolve Hull's longest running unsolved murder – of a young boy called Christopher Laverack, killed in the 1970s. They re-open the case, and sure enough, science leads them to his killer. One missing person case turns into two solved murders.